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<P><FONT SIZE="5">2.4 A Review Of FunnelWeb Syntax</FONT><BR>
<P>One of the disadvantages of FunnelWeb is its
clumsy macro definition and calling syntax. Compared to
(say) the C preprocessor, FunnelWeb's macro call syntax is
like a freight train in a china shop. Unfortunately, all
attempts to convert this syntax to something more elgant
have failed, because the existing syntax is the simplest
from a conceptual point of view and is the least likely
to cause semantic confusion. This page discusses and
justifies the FunnelWeb syntax.
<P><BR><FONT SIZE="4"><STRONG>Macro Definition Syntax</STRONG></FONT><BR>
<P>FunnelWeb's macro definition syntax results in
definitions that look like this:
<P><PRE>
@$@<Put out the cat@>==@{@-
Open the door
Say out
Close the door@}
</PRE>
<P>Here's why this syntax was chosen:
<P><BLOCKQUOTE><B>Dollars:</B> The <SAMP>@$</SAMP> is necessary to cue a
definition. Without it, the definition might somehow be
mistaken for an invocation.</BLOCKQUOTE>
<P><BLOCKQUOTE><B>Name delimiters:</B> The <SAMP>@<</SAMP> and
<SAMP>@></SAMP> are required to delimit the name and to
resonate syntactically with macro calls.</BLOCKQUOTE>
<P><BLOCKQUOTE><B>Content delimiters:</B> The <SAMP>@{</SAMP> and
<SAMP>@}</SAMP> delimit the content of the macro.</BLOCKQUOTE>
<P><BLOCKQUOTE><B>EOL suppressor:</B> The <SAMP>@-</SAMP> is a
result of the simplifying rule that the content of a macro
is "exactly the text between the
<SAMP>@{</SAMP> and <SAMP>@}</SAMP>."</BLOCKQUOTE>
<P>The only real target for a syntax purge the
"<TT>==</TT>" which is optional anyway.
<P>An alternative minimalist approach to macro definitions
is:
<P><PRE>
@<Put out the cat@>
Open the door
Say out
Close the door@}
</PRE>
<P>but this is too dangerous for my tastes as there
is no syntax surrounding the name of the macro to
indicate that it is a macro definition and not a macro
call.
<P><BR><FONT SIZE="4"><STRONG>Parameterized Macro Definition Syntax</STRONG></FONT><BR>
<P>The definitions of parameterized macros are even messier
than the normal definitions.
<P><PRE>
@$@<Put out the cat@>@(@3@)==@{@-
Open the door
Say out
Close the door@}
</PRE>
This is messy, but the "natural" alternative is even worse:
<P><PRE>
@$@<Put out the cat@>@(@1@,@2@,@3@)==@{@-
Open the door
Say out
Close the door@}
</PRE>
<P>Given that the parameters don't have names, it seems cleaner
just to specify the number of parameters.
pecifying the number of parameters seems sensible.
<P><BR><FONT SIZE="4"><STRONG>Macro Call Syntax</STRONG></FONT><BR>
<P>Here are some syntaxes that were considered for
FunnelWeb macro calls.
<P>
<PRE>
Open the door
@<Say Out@> @! Current style.
Close the door
Open the door
@<Say out>@
Close the door
Open the door
@"Say out@"
Close the door
Open the door
@(Say out@)
Close the door
Open the door
@<Say out>
Close the door
</PRE>
<P>Of these, the first was chosen.
<P><BR><FONT SIZE="4"><STRONG>Parameterized Macro Call Syntax</STRONG></FONT><BR>
<P>FunnelWeb V1 provided a messy parameterized macro
call syntax:
<P><PRE>
@<Say Out@>@(@"firstparam@" @,
@"Secondparam@" @,
@"thirdparam@" @)
</PRE>
<P>This syntax was cleaned up considerably in V3.0 by making
the <SAMP>@"</SAMP> symbols optional:
<P><PRE>
@<Say Out@>@(firstparam@,@-
Secondparam@,thirdparam@)
</PRE>
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